Agent Prentiss: There's a lot about Rachel that tells us about the UnSub. She was young, so most likely he was, too. Student: What makes you think that? JJ: Well she lived in a shelter and had a part-time job, so she was a street kid, but not necessarily the reckless type. She wouldn't just go off with anyone.

Agent Rossi: Now these two girls couldn't be more different. But the one thing they both have in common is that they both crossed paths with the most prolific killer the BAU has ever seen. Dr. Reid: What you need to understand is that no two killers are the same. They each occupy their own spot in the behavioral spectrum. Genetics, brain chemistry, psychology, they're all factors. Agent Hotchner: But we believe this particular killer grew up in an environment so adverse he never had a chance.